Kollam–Thiruvananthapuram trunk line is a railway line in Southern Railway zone connecting the cities of Kollam and Thiruvananthapuram in the state of Kerala, India. The line was opened on 4 January 1918 as the extension of Madras–Quilon line during metre gauge era.

The Kollam–Sengottai railway line is a railway line in South India which connects Kollam Junction in Kerala state and Sengottai in Tamil Nadu. The Quilon–Shencottah railway line was the first railway line in the erstwhile Travancore state and is more than a century old. The Kollam–Sengottai section is part of the Kollam–Chennai metre-gauge rail route commissioned by the British in 1904. The line has been completely converted to broad gauge and is now fully operational from Kollam Junction to Shengottai.It is the important cargo transportation line connecting Vizhinjam container port and South indian States.